Tube-filling machine and a filling method in such a machine

ABSTRACT

The invention provides tube-filling machines and methods for, in such machines, filling double tubes ( 10 ), that is to say the tube type which has concentric packing tubes ( 11, 12 ) which are connected to a common tube shoulder ( 13 ) provided with a dispensing opening. For filling the gap-shaped space between the inner tube and the outer tube, an elongate filling nozzle ( 18 ) is quipped on its output end with a peripheral set of filling pipes ( 18   f ) with output openings located radially inwardly in relation to the lateral surface of the filling nozzle and of smaller diameter than the gap. Located inside the filling nozzle is an elongate mandrel ( 20 ) of male type, and located on the outside around the open end of the outer tube is a centring sleeve ( 19 ) which maintains its position relative to the outer tube throughout the gap space-filling procedure.

The invention relates to tube-filling machines and filling method in such machines. More precisely, the invention relates to filling of double tubes. This means a tube of the kind which has an inner tube and, surrounding this with a gap, an outer tube, both connected to a common tube shoulder which has means for delivering product from the inner tube and the outer tube through an emptying opening in a desired way.

STATE OF THE ART

Double tubes of said kind and also other types of two-chamber or multi-chamber tubes are used for inter alia packing different types of products or components which, on mutual contact, react easily with one another chemically or in another way. It is desirable that such reaction occurs only in connection with the contents, in portions or completely, being emptied from the tube. Under such conditions, the components therefore have to be stored separately in the tube.

Applications other than that mentioned also exist. A double tube or other multi-chamber tube can be used, for example, to deliver “striped toothpaste”.

The document U.S. Pat. No. 1,676,734 discloses an early approach of sequentially filling inner- and outer tubes of double tube.

For rapid and reliable processing of said double tubes, however, an effective filling step and thus a commercially competitive tube-filling machine are lacking at present.

Such a tube-filling machine is to be capable of being used, with precision and high capacity, for producing defect-free, filled tubes without operational stoppages of the machine as a consequence of, for example, contamination in connection with filling, poor sealing of filled tubes or other hitches which disrupt functioning.

In order to achieve high output capacity, it is also to be possible when necessary for the filling, to carry out the filling in a parallel manner with a large number of tubes simultaneously in the filling station.

THE OBJECT OF THE INVENTION

Double tubes of the kind mentioned in the introduction have previously caused major problems, and it has not been possible effectively to fill such tubes in tube-filling machines without encountering the disruptions mentioned above.

The object of the invention is therefore to eliminate this disadvantage and to provide an effective filling process and a tube-filling machine for the double tubes.

THE INVENTION

The object of the invention is achieved by the filling method according to the method claim 1 and also by the tube-filling machine according to the machine claim 5.

Dependent claims linked to the respective main patent claims indicate advantageous developments.

DESCRIPTION OF THE DRAWINGS

The accompanying drawings show in a number of basic and detailed illustrations major structural elements forming part of the tube-filling machine for realization of the abovementioned object, in which drawings:

FIG. 1 shows a double tube in principle in its state before insertion into the tube-filling machine according to the invention,

FIG. 2 shows the double tube in FIG. 1 in its state when it leaves the tube-filling machine,

FIG. 3 shows in principle the processing steps for filling the gap-shaped space of the double tube between the inner tube and the outer tube, and

FIG. 4 shows a perspective illustration of the filling nozzle for said gap-shaped space,

PREFERRED EMBODIMENT OF THE INVENTION

The double tube 10 in FIG. 1 has an inner tube 11 and an outer tube 12.

These two tubes are connected to a tube shoulder 13, in which there are passages (not shown) for separate dispensing and subsequent mixing of the contents of the inner tube 11 and the gap-shaped space between the inner tube and the outer tube. There is a tube cap 14 on the tube shoulder.

In the embodiment shown, the inner tube, the outer tube, the tube shoulder and the tube cap all have a circular cross section, which is to be preferred with the filling step which will be described below.

In principle, however, other cross-sectional shapes are possible.

The selection of material for the double tube components depends on the intended application. Thermoplastics of the polyolefin type, for example polyethylene, polypropylene etc. with or without barrier layer, are usually used. In order to apply the hot-gas activation technique and heat-sealing method which are described in our co-pending divisional Swedish patent application No 0203294-4, however, it is essential that the open end portions of the double tube in FIG. 1 comprise material which is heat-sealable.

The double tube 10 is inserted into the tube-filling machine directly from transport packs filled with a large number of tubes and supplied by a tube manufacturer. The tubes can be greatly deformed and deviate considerably from their nominal (circular) cross section at the open end. The double tube shown in FIG. 1 intended for insertion into the tube-filling machine deviates moderately from the nominal cross section. In view of the fact, however, that the gap between the inner tube and the outer tube has a relatively small width, for example of the order of 5 mm, handling is inevitably a delicate operation, chiefly in connection with filling the gap space, but also during thermal activation for subsequent sealing.

It is moreover another important task, with the narrow gap space and where appropriate different kinds of material in the inner tube and the outer tube, to bring about leakproof and aesthetically attractive end sealing of the double tube. Such end sealing can be seen in FIG. 2. A special thermal activation process for this important task, is disclosed in the divisional Swedish patent application mentioned earlier.

FIG. 3 shows in principle the processing steps according to the invention for filling the gap-shaped space between the inner tube and the outer tube. The double tube 10 is supported in a tube holder 15. This is located on an endless conveyor 16 supported by a machine frame (not shown) and driven stepwise in order to convey tubes, individually or in groups, to work stations in order to process them.

A lifting device 17 is shown in the filling station in FIG. 3 and can be applied to the underside of the tube holder 15 in order to adjust the vertical position of the tube holder and thus the tube vertically upwards and downwards.

Located vertically above the tube 10 in FIG. 3 is a filling nozzle 18 which, in the embodiment shown, is supported in a stationary manner in the machine frame. A vertically upwardly and downwardly adjustable centring sleeve 19 of circular inner cross section surrounds the lateral surface of the elongate, cylindrical nozzle 18 with a gap which makes possible insertion of the end of the outer tube into the gap space. The inner cross section (circular in the embodiment shown) of the centring sleeve corresponds to the cross section of the end of the outer tube, and the cross section is intended to give this end its nominal cross section and dimension. By means of the centring sleeve, the requisite well-defined shape of the outer tube end is thus created and/or guaranteed from the outside of the double tube.

Before the processing steps shown in FIG. 3 are described, a more detailed description of the filling nozzle 18 is required, and reference is made to FIG. 4 for this.

The filling nozzle is elongate and has a circular-cylindrical outer lateral surface which, together with the centring sleeve 19 mentioned, is intended to receive the outer tube 12 of the double tube between itself and the centring sleeve. Located slightly inside said lateral surface radially, with uniform mutual spacing along the entire periphery of the lateral surface, is a set of filling pipes 18 f. The mouths of these pipes have a relatively small diameter, of the order of a few mm, a diameter which is obviously smaller than the gap width between the inner tube 11 and the outer tube 12 of the double tube. As mentioned previously, the space intended for filling between the inner tube and the outer tube is narrow, and it is essential that product is not accumulated on the outside of the filling pipes and the lateral surface of the nozzle. With a small diameter of the mouths of the filling pipes, it is relatively easy to interrupt the product supply rapidly and accurately.

An elongate, hollow mandrel 20 of male type is arranged in the nozzle coaxially with its lateral surface along the entire length of the nozzle, and a bevelled entry end 21 projects a little way beyond the mouths of the filling pipes 18 f. In the illustrative embodiment shown, the mandrel 20 has a circular cross section corresponding to the nominal circular inner cross section of the inner tube 11. This means that the inner tube is necessarily shaped to the nominal cross section when the filling nozzle 18 with its mandrel 20 is located in the double tube 10. The outer tube of the double tube lies with its inner side centered around the lateral surface of the filling nozzle and is shaped by the centring ring 19 to nominal circular cross section. In this way, a well-defined space intended for filling is created between the inner tube and the outer tube. In this space, the openings of the filling pipes 18 f are in well-defined positions for filling said gap-shaped space without interference and deposit on the nozzle.

In order that this space will be well-defined throughout the filling step, it is ensured that the centring ring 19 maintains its position relative to the double tube throughout the filling step. The preferred position in the illustrative embodiment is a position around the open end portion of the double tube.

In the illustrative embodiment, the filling nozzle 18 is stationary in the machine frame, while the tube 10 is adjustable in the vertical direction.

It is thus a matter of synchronizing the movement of the tube holder 15 with the movement of the centring sleeve 12. In the illustrative embodiment, this is brought about by synchronized servo-driven units (not shown).

FIG. 3 shows the operations making up a complete filling step for filling the gap-shaped space between the inner tube and the outer tube.

In position a, the advance of the conveyor 16 has been stopped. The tube holder 15 is in its transport position, the lifting device 17 is not in contact with the tube holder, and the centring sleeve 19 is in a position with a gap surrounding the dispensing end of the filling nozzle.

With the advance stopped, the lifting device 17 is then applied, and the open end of the double tube is centred externally by the centring sleeve 19 and internally by the mandrel 20, that is to say the outer tube is given a circular cross section by the centring sleeve, and the inner tube is necessarily shaped to a circular cross section on the mandrel 20. This takes place in step b.

In step c, the double tube has been lifted by the lifting device 17 to a position in which the mouths of the filling pipes 18 f lie close to the tube shoulder and are positioned in an interference-free manner in the gap-shaped space between the inner tube and the outer tube. The centring sleeve 19 has been moved vertically upwards (by the servo unit, as has the tube holder) and maintains its relative position in relation to the open end of the double tube.

The mandrel 20 lies inside the inner tube 11. Filling of the gap-shaped space can thus begin. During this process, the tube holder 15 and the centring sleeve 19 are drawn downwards (by their servo units) until the tube returns to the position in step b. Throughout this procedure, the centring sleeve 19 maintains its position relative to the double tube. In step d, filling of the gap-shaped space between the inner tube and the outer tube has been completed, and the tube holder 15 then returns to transport position, step e. It remains to fill the inner tube 11 with the product intended therefor. The double tube 10 is advanced to the next filling station. From the filling point of view, the inner tube 11 is in principle a conventional single tube, but with improved dimensional stability brought about by filling of the gap-shaped space, and can thus simply be filled by a filling nozzle intended for single tubes.

The invention thus provides a tube-filling machine, and preferred processing method for filling of double tubes have been described. In the description made with reference to the drawings, the principles underlying the invention are shown on the one hand diagrammatically and on the other hand by specific embodiments of components.

Such components can of course vary in their design within the scope of the accompanying patent claims, and the intention is that the invention is to be limited only by the content of the accompanying patent claims. 

1. Method for, in a tube-filling machine, filling tubes (10) of the kind which has an inner tube (11) and, surrounding this with a gap, an outer tube (12), both connected to a common tube shoulder (13) which has means for delivering product from the inner tube and the outer tube through an emptying opening in a desired way, tubes being fed, individually or alternatively in groups, to a filling station (18,) located along a conveyor path, by a conveyor (16) working stepwise, in the requisite order for processing, the tube(s) being filled in the filling station, and the tube(s) after sealing, being delivered from the tube-filling machine in a feed-out station, characterized in that, in a filling station, the gap of a tube (10) between the inner tube (11) and the outer tube (12) is first filled by means of an elongate nozzle (18) which can be introduced into the gap, is provided with a centrally positioned mandrel (20) of male type, is equipped with filling pipes (18 f) and has product-delivery openings corresponding to the gap configuration, as a first step the open end of the outer tube (12) being provided with its nominal cross section and being centred relative to the nozzle by means of a centring sleeve (19) located externally around the nozzle, and at the same time the open end of the inner tube being provided with its nominal cross section and being centred relative to the nozzle by means of said centrally positioned mandrel (20) of male type, in that then, with outer and inner tubes centred, said nozzle (18) is positioned in its initial position for the start of filling, at a short distance from the tube shoulder (13), in that then, with the centring sleeve (19) being retained around the open tube end, the nozzle (18) is guided in the direction out of the tube, from said start-of-filling position to a final position corresponding to a desired filling level, and in that then the inner tube (11) is filled by means of a filling pipe which can be introduced centrally into the inner tube.
 2. Method according to claim 1, characterized in that relative movement between the nozzle (18) and the tube is brought about by means of a nozzle supported in a stationary manner in the machine frame, a tube holder (15) which can be raised and lowered vertically in the frame, and a centring sleeve (19) which can be raised and lowered vertically in the frame and is synchronized with the movement of the tube holder.
 3. Method according to claim 2, characterized in that the nozzle is made with a number of filling pipes (18 f) positioned with essentially uniform mutual spacing externally around the entire periphery of the circumference of the central mandrel (20).
 4. Method according to any one or some of the preceding claims, characterized in that the tubes which are processed have an outer tube (12) and an inner tube (11) with a tube body of circular-cylindrical shape, at least along the majority of the body from the open end thereof.
 5. Tube-filling machine for filling tubes (10) of the kind which has an inner tube (11) and, surrounding this with a gap, an outer tube (12), both connected to a common tube shoulder (13) which has means for delivering product from the inner tube and the outer tube through an emptying opening in a desired way, tubes being fed, individually or alternatively in groups, to a filling station (18) located along a conveyor path, by a conveyor (16) working stepwise, in the requisite order for filling, the tube(s) being filled in the filling station, and the tube(s), after sealing, being delivered from the tube-filling machine in a feed-out station, characterized by an elongate nozzle (18) which can be introduced into the gap between the inner tube (11) and the outer tube (12), is provided with a centrally positioned mandrel (20) of male type, is equipped with filling pipes (18 f) and has product-delivery openings corresponding to the gap configuration, a centring sleeve (19) located externally around the nozzle, means for bringing about relative movement between the tube (10) and the nozzle (18), and means for constantly holding the centring sleeve in position around the open tube end during relative movement between the tube and the nozzle.
 6. Tube-filling machine according to claim 5, characterized in that said means for relative movement between the tube and the filling nozzle comprise a tube holder (15) which can be raised and lowered vertically and is supported with servo control in the stand and a filling nozzle (18) supported in a positionally fixed manner in the stand, and in that said means for holding the centring sleeve around the open tube end comprise a servo-driven unit synchronized with the first-mentioned.
 7. Tube-filling machine according to claim 6, characterized in that the nozzle has a number of filling pipes (18 f) positioned with essentially uniform mutual spacing externally around the entire periphery of the central mandrel.
 8. Tube-filling machine according to claim 7, characterized in that the elongate nozzle (18) is essentially circular-cylindrical with the filling pipes (18 f) lying well inside the lateral surface of the nozzle, and in that the central mandrel (20) is essentially cylindrical with a conical entry end (21). 